4 minute read
Interview
Green design in full flow
Bob Cramblitt talked to architectural, engineering and interiors planning firm SmithGroup about sustainability and the role of Computational Fluid Dynamics (CFD) in the green architectural movement.
SmithGroup, a US architecture, engineering, interiors and planning firm, says sustainable design is at the core of every one of its projects. To help with the engineering design and construction of new buildings and retrofits of existing facilities, SmithGroup performs comprehensive energy modelling, as well as computational fluid dynamics studies.
Bob Cramblitt: How does SmithGroup show clients the energy efficiency of its designs as they are being developed?
SmithGroup: Energy efficiency is evaluated throughout all design phases. During schematic level and early design development phases we often determine the passive design strategies we can use to reduce the overall building energy consumption without causing a negative effect on other elements of the building.
A good example of this is analysing solar shading in order to reduce energy losses through glazing without reducing daylighting. These types of analysis are explained through presentations or reports that run through all the scenarios analysed and highlight which scenario is the best choice for the desired outcome.
In later design phases we often focus on the overall heating, ventilation, and air conditioning (HVAC) system efficiencies. The combination of passive and active strategies allows the overall size of the HVAC system to be smaller and use highly efficient pieces of equipment that greatly reduce overall energy consumption.
BC: How does Computational Fluid Dynamics (CFD) fit into your sustainable design efforts?
SG: As the demand for sustainable design increases, so does the demand to be on the forefront of new technologies. This often means dealing with long-term untested practices.
Using CFD upfront in the design process has allowed SmithGroup to confidently implement new technology and ideas through proof of concept verification. A room with a chilled beam system can be modelled quickly and easily during the design process to ensure thermal comfort will be maintained.
Another good example is the use of CFD to determine the feasibility of a natural ventilation design for a retrofit of an existing building. SmithGroup used Autodesk CFdesign software to determine whether a building that originally implemented natural ventilation in 1881 was capable of providing enough natural ventilation after 100 years of urban growth around it.
A CFD simulation from Autodesk CFdesign showing complex airflow patterns at the L’Enfant Plaza in Washington, D.C. The simulations helped SmithGroup properly design and size HVAC systems for greater energy efficiency.
SG: At SmithGroup, architectural and engineering design teams collaborate at very early stages of design in order to create a fully integrated practice. During these early design stages important decisions need to be made based on schematic-level energy analysis and CFD studies that greatly affect the overall design. A relatively small effort early can produce invaluable information to help both the architect and engineer better understand a project. This information ensures we are creating an energy-efficient building and also producing the best product for our client.
BC: What specific attributes do you look for in a CFD program and why?
SG: A CFD program must be user-friendly. CFD programs have come a long way in this regard over the last few years. Earlier CFD programs were far from user-friendly and this created a misconception that CFD can only be done by a select number of users. That is far from the truth with today’s programs. SG: Mechanical engineers are the sole CFD users at SmithGroup. After the simulation has been run the mechanical engineer working on the project will discuss the results with the design team, and improvements or changes to the design will be made. This process will be run through as many iterations as required to produce the results for which we are looking.
BC: What kind of cultural changes are required to integrate CFD into design and engineering processes?
SG: The biggest change needs to be early integration. Often times consulting engineering firms will be brought onto a job after the early phases of design have already been developed by an architectural firm. By this point critical decisions have already been made without a full understanding of the design.
BC: What BIM or CAD program do you use and how important is the interface with your CFD software?
SG: SmithGroup was an early adopter of Autodesk Revit and has made a transition to working almost exclusively in Revit. The CFdesign plug-in makes exporting Revit models into the program as easy as a single button click. This helps streamline the process, allowing us to spend more time on the design rather than setting up a model.
BC: Do you think sustainability is going to continue being a watchword for the future?
SG: Sustainable design is here to stay. As we progress, the challenges of creating more environmentally responsible designs will increase and will begin to push the envelope of building design and technologies. This challenge will require architects and engineers to constantly expand their perception of sustainable design and push current boundaries to reduce our overall impact on the environment.
